Security readout for executives and security teams
Plain-English summary
This vulnerability can let a highly privileged attacker remotely execute code on affected Microsoft Exchange Server installations. Successful exploitation could compromise email confidentiality, alter data, and disrupt service. The listed versions are older Exchange 2013, 2016, and 2019 cumulative updates.
Executive priority
Treat remediation as urgent because CISA records known exploitation and successful attacks could fully compromise Exchange data and availability. Prioritize patch verification on externally reachable servers, while recognizing exploitation requires an existing high-privilege position.
Technical view
CVE-2021-31196 is a network-reachable Exchange Server remote-code-execution vulnerability with CVSS 3.1 score 7.2. Exploitation requires high privileges but no user interaction and has high confidentiality, integrity, and availability impact. The supplied sources do not identify a CWE or explain the underlying flaw.
Likely exposure
Exposure is limited to organizations running Exchange Server 2013 CU23, 2016 CU20 or CU21, or 2019 CU9 or CU10. Network accessibility creates an attack path, although the CVSS vector indicates an attacker must already possess high privileges. The bundle does not identify affected hosted Exchange services.
Exploitation context
CISA lists CVE-2021-31196 in its Known Exploited Vulnerabilities catalog, supporting evidence of exploitation in the wild. The supplied evidence does not describe exploitation frequency, targets, indicators, or a public exploit. High privileges are required before remote code execution is possible.
Researcher notes
The evidence establishes network attackability, low attack complexity, high required privileges, no user interaction, and complete impact categories. It does not provide root-cause details, CWE classification, exploit mechanics, indicators of compromise, or affected configurations beyond the listed cumulative updates. Avoid inferring a specific vulnerability class.
Mitigation direction
- Apply the Microsoft security update referenced by the vendor advisory.
- Upgrade Exchange systems to a currently supported and fully patched cumulative update.
- Prioritize affected servers that are reachable from untrusted networks.
- If immediate patching is impossible, consult Microsoft guidance for supported temporary protections.
Validation and detection
- Inventory Exchange Server editions, cumulative updates, and installed security updates.
- Compare each deployment against the five affected cumulative updates in the source bundle.
- Confirm Microsoft's CVE update is installed using approved patch-management records.
- Review affected servers for suspicious privileged access and unexpected post-compromise activity.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-31196 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.2 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.25.9microsoftVulnerability scoring details
Base CVSS 3.1 score
7.2HighVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft Exchange Server Remote Code Execution VulnerabilityCVE reference, microsoft · vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31196CVE reference, CVE · x_refsource_MISC, x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31196CVE reference, CISA-ADP · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.